2020-1-13 On your Mac, your photo collection is separated into four main categories: Years, Months, Days, and All Photos. The All Photos tab shows all your photos and videos in chronological order. In Years, Months, and Days, you'll find your photos and videos grouped together based on the time and place they were taken. Using iMusic to Merge iTunes Library Effortlessly. The next method that we’re going to look at allows you to easily merge iTunes library without too much hassle on your Mac or Windows. This is the best method available and on top of that, iMusic – Music Manager & Download is a program which has a lot more to offer than just this.
Your Photos library holds all your photos, albums, slideshows, and print projects. If your library is large, and you want to free up storage space on your Mac, turn on iCloud Photo Library and use Optimize Mac Storage, or move your library to an external drive.
Before you start, be sure to back up your library.
You can store your library on an external storage device, such as a USB or Thunderbolt drive formatted as APFS or Mac OS Extended (Journaled).1 Find out how to check the format of your external storage device.
To prevent data loss, Apple doesn't recommend storing photo libraries on external storage devices like SD cards and USB flash drives, or drives that are shared on a network.
After you open your library from its new location and make sure that it works as expected, you can delete the library from its original location.
In a Finder window, go back to your Pictures folder (or whichever folder you copied your library from) and move Photos Library to the trash. Then choose Finder > Empty Trash to delete the library and reclaim disk space.
If you have multiple libraries, here's how to open a different one:
Photos uses this library until you open a different one.
If you have a permissions issue with your library, you might be able to resolve the issue by using the Photos library repair tool.
1. You can't move your library to a disk that's used for Time Machine backups.
2. If the volume isn't formatted APFS or Mac OS Extended (Journaled), or has been used for Time Machine backups but hasn't been erased, this checkbox will either not be present, or won't be selectable after unlocking. Erase and reformat the drive for this option to be available.